Why do parents think they know everything?

With age comes wisdom, while you may think that it's annoying, really they do what they think is best for you. This sounds cliche I know, but parents are there for a reason, and someday you may thank them for that

they're older than us and they've seen the world and that makes them think that they know everything but it's really not important that they actually know everything even if they say so.

As you get older you realize that they may not be perfect or know everything but usually there's extreme value to what advice they give you. Much knowledge is gained through experience, so they have some insights that you have not yet reached. My parents loved me more than anyone in this world and I hope yours do as well. It seems smart to take advice and to listen to someone who cares about you that much, because they truly just want what's best for you.

Because well they have been on this planet longer than you and they have finished school so they think they know everything.

They lived their life, and they're trying to warn their kids about the mistakes they have made to keep their kids from making the same ones.

I don't think they think that. I believe they are trying to instill their knowledge because they do have some. I think though, sometimes, they tend to talk to their kids more than listen to them.

Because they do know what's right for their child. They would never want to hurt their child or want them be hurt other ways.

Parents think they know everything because they "have gone through the same stuff." i dont think so!

there are 2 reasons. The first is that they remember when their children were born. And knew nothing. And after years of answering their questions, and explaining why things are as they are, they just got into a habit of explaining stuff. The second reason is that sometimes they see more than their children do, but they aren't quite sure how to say that without sounding like they are correcting them.

Well parents don't necessarily know everything nor do they think they do. Parents want to feel like they know the best for their child and to feel like they are a good parent. They naturally just want the best for you :)